In order to enable piezoelectric blade assemblies mounted onto a circuit board to maintain desired vibration and performance, a conventional approach as shown in FIG. 1 is to add a protection frame 20′ above a piezoelectric blade 10′. And the piezoelectric blade 10′ and the protection frame 20′ are interposed by an elastic element 30′ therebetween on the vibration node to prevent the piezoelectric blade 10′ from being compressed by external forces and broken, and also allow the piezoelectric blade 10′ to be anchored more securely. However such a structure still has drawbacks, notably:
1. The protection frame 20′ has to individually cover the piezoelectric blade 10′. For a structure that has many sets of piezoelectric blade 10′ laid in a juxtaposed manner, fabrication process and time increase. The cost for producing many protection frames 20′ also increases.
2. The protection frame 20′ generally completely covers the piezoelectric blade 10′. Heat energy generated by vibration of the piezoelectric blade 10′ cannot be dispersed. Moreover, the piezoelectric blade 10′ also produces friction noise during vibration. The sealed protection frame 20′ creates acoustic chest effect and results in excessive noise during operation of the piezoelectric blade 10′.
3. Different loads (such as cold cathode fluorescent lamps) require different output powers of the piezoelectric blade 10′ (such as different length and luminosity). Hence the number of layers of the piezoelectric blade 10′ varies. The height of single sheet or laminated piezoelectric blade 10′ has to change according to the load condition. As a result, different heights of protection frame 20′ have to be designed to match the piezoelectric blade modules of different specifications and heights. The number of specifications of the protection frame 20′ increases and the fabrication is higher.